139043521 has 4 divisors (see below), whose sum is σ = 142801492. Its totient is φ = 135285552.

The previous prime is 139043519. The next prime is 139043557. The reversal of 139043521 is 125340931.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125340931 = 131 ⋅956801.

It can be written as a sum of positive squares in 2 ways, for example, as 83466496 + 55577025 = 9136^2 + 7455^2 .

It is a cyclic number.

It is not a de Polignac number, because 139043521 - 2¹ = 139043519 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 139043521.

It is not an unprimeable number, because it can be changed into a prime (139943521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1878930 + ... + 1879003.

It is an arithmetic number, because the mean of its divisors is an integer number (35700373).

Almost surely, 2^139043521 is an apocalyptic number.

It is an amenable number.

139043521 is a deficient number, since it is larger than the sum of its proper divisors (3757971).

139043521 is an equidigital number, since it uses as much as digits as its factorization.

139043521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3757970.

The product of its (nonzero) digits is 3240, while the sum is 28.

The square root of 139043521 is about 11791.6716796220. The cubic root of 139043521 is about 518.0642042131.

It can be divided in two parts, 13904 and 3521, that multiplied together give a palindrome (48955984).

The spelling of 139043521 in words is "one hundred thirty-nine million, forty-three thousand, five hundred twenty-one".